When a projection system projects onto a non-uniform surface, local aspect ratio distortion can occur. For example, surface irregularities of the projection surface can cause the projected image to be distorted as observed from an observer perspective. In addition to screen surfaces being irregular, keystone distortion can occur when the projection optical axis is not perpendicular to the screen. The combination of keystone and projection surface distortion can severely limit the ability of an observer to correctly perceive the projected images.